Just as he did in Terminator 2, which is the most successful sequel in history, James Cameron should look for a way to bring our hated yet loved badass villian, Quartich to the good side.

One way this could be done is from what most of us know already, that the sequel won't involve humans as the bad guys but aliens instead. This gives both the Na'vi and Quaritch/humans a common enemy, which gives JC a logical way to make Quaritch a (possibly reluctant) good guy.

Quaritch is arguably the most interesting character in Avatar and always provides a thrill when on-screen. I feel the sequel will be missing something if Quaritch fails to make a (re)appearence.

The most recent example of this being done was in the movie Pirates of the Caribbean: Dead Man's Chest and its third installment, At World's End, where Captain Barbossa, once the main villain in the first movie, and the good side both found a common enemy in the British Navy and Davy Jones and joined sides.

The downside is, is that it might be too predictable and once again the public will have a problem with a "predictable" plot.